Abstract
Patients with central vision loss often adopt eccentric viewing strategies using a preferred retinal location (PRL) in the absence of functional foveae. Little is known about the oculomotor characteristics of the PRL under binocular eye-hand coordination. We examined PRL location, fixation stability and smooth pursuit under binocular viewing using simulated gaze-contingent scotomas in normally-sighted observers. Participants (N=7) completed two eye-hand coordination tasks in two conditions with gaze-contingent central scotomas. Scotomas were updated at 60Hz refresh rate based on a 500Hz eye tracker. In a fixation task, participants touched a target in the center of the screen with their hand. In a pursuit task, participants followed a horizontally oscillating target with their hand. In the second condition, participants viewed a picture of a hand that moved in same touch positions as previous trials in the fixation and smooth pursuit tasks. Participants completed two runs of each condition. Outcome measures were fixation stability (BCEA, 68%), PRL eccentricity and stability of smooth pursuit. PRL eccentricity increased with scotoma size (p < .001), but BCEA did not vary as function of scotoma size, task or condition (ps > 0.05). There was a significant interaction between run and condition (hand vs picture): PRLs were closer to the target in second run of the hand but not picture condition (p = 0.05). Smooth pursuit stability decreased with increasing scotoma size and was greater in the own hand than picture condition (p < .01). Smooth pursuit but not fixation stability varied as function of scotoma size and hand condition. There was a training effect for PRL location in the hand condition, suggesting that PRL use may adapt under eye-hand coordination. These differences offer insight into how the coupling of eye and hand movement may influence binocular visual function in patients with central vision loss.
Acknowledgement: 1 R01 EY029713